[Guide] (OS X) upgrade or downgrade FW using Cydia SHSH with iTunes
Please refer to: Caching Apple's Signature Server - Jay Freeman (saurik)
On Mac OS X, Open a terminal session and type:
Step 1: - Going in to the Host file
sudo nano /etc/hosts
enter your Mac OS X system password when promoted.
Step 2: - Entering the Cydia Sauriks server line
Hit the down arrow until you get to the end of the file, and add Cydia host:
Ö I put in an extra line break at the end. I donít think itís really necessary but itís a habit from having to use Windows, which would ignore the last line in a hosts file.
Step 3: Ė Save the hosts file
When done editing the hosts file, press control-o to save the file.
Press enter on the filename prompt, and control-x to exit the editor.
Step 4: - Flushing the cache to get the server file to work.
Open mobile terminal again and enter:
sudo dscacheutil -flushcache
Öthe server should now resolve! Test it:
ping 22.214.171.124 gs.apple.com
Open iTunes and now you can restore you firmware to whatever SHSH blog is on file with Cydia on your iPhone.